Individual iron club heads in a set typically increase progressively in face surface area and weight as the clubs progress from the long irons to the short irons and wedges. Therefore, the club heads of the long irons have a smaller face surface area than the short irons and are typically more difficult for the average golfer to hit consistently well. For conventional club heads, this arises at least in part due to the smaller sweet spot of the corresponding smaller face surface area.
To help the average golfer consistently hit the sweet spot of a club head, many golf clubs are available with cavity back constructions for increased perimeter weighting. Perimeter weighting also provide the club head with higher rotational moment of inertia about its center of gravity. Club heads with higher moment of inertia have a lower tendency to rotate caused by off-center hits. Another recent trend has been to increase the overall size of the club heads, especially in the long irons. Each of these features increases the size of the sweet spot, and therefore makes it more likely that a shot hit slightly off-center still makes contact with the sweet spot and flies farther and straighter. One challenge for the golf club designer when maximizing the size of the club head is to maintain a desirable and effective overall weight of the golf club. For example, if the club head of a three iron is increased in size and weight, the club may become more difficult for the average golfer to swing properly.
In general, the center of gravity of these clubs is moved toward the bottom and back of the club head. This permits an average golfer to get the ball up in the air faster and hit the ball farther. In addition, the moment of inertia of the club head is increased to minimize the distance and accuracy penalties associated with off-center hits. In order to move the weight down and back without increasing the overall weight of the club head, material or mass is taken from one area of the club head and moved to another. One solution has been to take material from the face of the club, creating a thin club face. Examples of this type of arrangement can be found in U.S. Pat. Nos. 4,928,972, 5,967,903 and 6,045,456.
Iron-type clubs, which include wedge clubs, are typically made by investment casting, machining or forging. Forged club heads are coveted by the higher skilled amateur golfers and professionals for its superior playing characteristics. On the other hand, forgeable alloys are malleable and typically have low yield strengths. For forged clubs, the face of the club cannot heretofore be made thin, because of this drawback.
Commercially available forged iron-type clubs are typically the muscle back type, such as the Titleist® Forged 670, 680 and 690 series, Mizuno's MP-33 irons and Kenneth Smith's Royal Signet clubs. The Royal Signet® muscle back clubs concentrate the club weight near the center sweet spot, thereby reducing its moment of inertia. Forged cavity back iron-type clubs are also available, as midsize clubs with relatively thicker hitting face, such as the Titleist® 690-CB, the Hogan Apex Edge Pro or the Royal Signet® Titanium. The Hogan Apex Edge Pro irons are single-piece clubs forged from carbon steel, but the Hogan CFT clubs have a stamped titanium face in a cast body. The Royal Signet® Titanium clubs are cast stainless steel clubs with a forged titanium full face insert for additional strength.
Hence, a need still exists for improved forged iron-type golf clubs.